The PEPSI Exoplanet Transit Survey (PETS). V: New Na D Transmission Spectra Indicate a Quieter Atmosphere on HD 189733B

Absorption lines from exoplanet atmospheres observed in transmission allow usto study atmospheric characteristics such as winds. We present a newhigh-resolution transit time-series of HD 189733b, acquired with the PEPSIinstrument at the LBT and analyze the transmission spectrum around the Na Dlines. We model the spectral signature of the RM-CLV-effect using syntheticPHOENIX spectra based on spherical LTE atmospheric models. We find a Na Dabsorption signature between the second and third contact but not during theingress and egress phases, which casts doubt on the planetary origin of thesignal. Presupposing a planetary origin of the signal, the results suggest aweak day-to-nightside streaming wind in the order of 0.7 km/s and a moderatesuper-rotational streaming wind in the order of 3 - 4 km/s, challenging claimsof prevailing strong winds on HD 189733b.